Friday, 7 December 2007
Paul Freemantle: A new kind of (SOA) Registry
Thursday, 6 December 2007
After Service_1.0: The Service Interface Version Adapter Pattern
- Means that clients already using the interface won't 'break' the service interface.
- Allows service implementations (and clients, potentially) to dynamically determine the service version based on a message.
Wednesday, 5 December 2007
SOA Rules of Engagement
- Don't forget the constructive tension. For SOA to be a success, there needs to be a tension between the desire to do things now, and the desire to do things right. This means setting up a governance function to complement (note: complement, not obstruct) your delivery function.
- Don't forget to deliver something useful early. SOA business cases are notoriously hard, because many (not all) of the benefits arrive in the longer term, and will only be realised if other projects behave as expected. By far the best way to get on in this world is to deliver some business benefit early. Your sponsors will thank you, and it's not as hard as you think - SOAs are all about managing change afterall, so you can do a lot just by delivering a sequence of relatively small incremental projects.
- Don't boil the ocean, the fish won't like it. Many many SOA projects try and 'SOA-enable' huge swaithes of their technical architecture in one foul swoop. It's a well established near-fact that it's difficult or impossible to achieve. I've only worked on one project where this worked, and that was because it was a spin-off from a large company, and so had only a small amount of 'heritage' (nee legacy) systems to contend with - most of the services were built from the ground up.
- Don't worry about the technology. Technology is usually far from the biggest risk to a large SOA programme. Weak benefits cases, poor governance, poor expectation management or a changing political/economic environment are far more likely to be your downfall.
- Do worry about the technology. Having said that technology is not the biggest risk, it is a significant risk. Keep it simple. Implement just the functionality and infrastructure you need in the first instance. Don't believe people or companies that tell you that SOA is a product, or is simply a technical problem that they can solve for you.
- Do get strong project management, but keep them in their box. As I've alluded to above, there are tons of risks waiting to consign your SOA aspirations to the great ESB Gateway in the Sky, so you'll need an excellent project manager to manage them for you. By excellent, I don't mean they're a dictator, I mean they're an enabler for your team, and a black belt in motivation, reporting, and risk management. Whatever you do: If they're running the delivery of a project, do not allow them to become responsible for your organisation's SOA governance. There be dragons.
- Do get an all star cast (at least initially). The nature of SOA is such that there is a lot of opportunity for working smarter rather than harder, which will get you to market faster, make your SOA easier to maintain, and cost you less. Get yourself a team of technical people who really know their bananas; quality is vastly more important than quantity. Seriously consider going outside your organisation to secure at least part of your core team - the people in the next room might be brilliant, but experience is everything in the SOA world. Architects, business/system analysts, developers and testers are all important, and you'll need them to work in perfect harmony for your SOA to really take off.
- Do make sure you're involved. It might be tempting at times to bury your head in the sand, and allow someone else to 'do SOA to you', but don't let this happen. While it's important to get that all star cast, it's also critical that your organisation learns from any 'outsiders', and will be capable of taking the reigns in the long term. That said, do consider keeping outsiders in the mix for the long haul - the world is changing rapidly, and keeping people who've seen other organisations make mistakes close to you will enable you to dodge the pitfalls that consume your competitors.
IBM WebSphere Process Server and Apache Tuscany: Not in love. Yet.
I've just spotted a post on Bobby Wolfe's blog discussing the relationship between Apache Tuscany and WebSphere Process Server. He has confirmed that WPS will not be based on the Tuscany runtime.
I've been using Process Server since before it went GA way back in late 2005, and at the time, Tuscany was more embryo than fully fledged citizen of the SOA world. It drew my attention even then, because WPS - despite being a brand new product - was flying the SCA flag without actually being capable of implementing the 1.0 standard. Unfortunately for IBM, the last point release of the standard had made some fairly significant changes to the way code was structured into modules, which might have made it hard for IBM to implement the 1.0 standard on their existing architecture.
The combination of these inherent limitations, and IBM's bundling of Tuscany within the (snappily titled) IBM WebSphere Application Server Version 6.1 Feature Pack for SOA meant that we always assumed IBM would ultimately migrate Process Server across to the Tuscany, with the value add coming from IBM's established process, mapping and rules engines. Since the feature pack was out for 6.1, we had hoped (perhaps beyond hope) that this would happen as part of the WPS 6.1 release, which it would seem now is not the case.
This is something of a disappointment for me, as our architecture was being made significantly more complex than it needed to be because of the lengths we had to go to to re-use 'service capabilities' (more on these another day) across services.
I'm still 99% sure IBM will make this transition at some stage - they'd be crazy not to in my opinion, since there is plenty of value add IBM can provide in the components that sit on top of the SCA runtime, and every dollar they save working on the runtime they can use to add new glossy features to the remainder of the product.
My money is on WPS 7.0. How about you?
Sunday, 2 December 2007
Next time you have brain surgery...
...it might be best to avoid:
In the former case, the hospital is "re-evaluating its training and policies". Perhaps they should start by investing in surgical gowns with "Left" and "Right" stitched into the seams.